Relevant Resource questions :

Concepts demonstrated :

• convection
• convection streams

• beaker filled with water
• retort stand and wire gauze
• bunsen burner and matches
• potassium permanganate crystals
• CCD camera

• Place crystals in a beaker filled with water.
• Heat the beaker of water over a bunsen.

None.

Physics involved :

Convection in a liquid. The potassium permanganate crystals dissolve when the water is heated. Heating the water causes convection currents to occur. The dissolved crystals map out the convection currents.

How to use the Demonstration :

• Demonstrate convection in a liquid.

Things to do or add :

• Replace the beaker with a narrow and long box. Perhaps 20cm high by 30cm long but only 2cm wide. This would restrict the convection essentially to two dimensions.

• How about a demo showing Newton's Law of Cooling ? (dQ/dt proportional to delta Tau). It applies when all 3 mechanisms are operating. Various relationships can describe the rate of heat transfer with different conditions in convection.